Nowadays, mobile communication devices capable of connecting to wireless local area networks (LANs) are used. Access points (also referred to as base stations) equipped with wireless interfaces are provided at various locations in a wireless LAN. For example, a mobile communication device searches for available access points located in the surrounding area (this operation will alternatively be referred to as scanning, as needed). If the mobile communication device detects that an access point satisfies a predetermined condition and that the signal level received from the access point is above a connection threshold, the mobile communication device connects to the access point automatically or in accordance with an instruction from the user, so as to perform wireless communication through the access point.
In one proposed access point selection method, home networks that a mobile communication device use most frequently are distinguished from remote networks that the mobile communication device use while away from the home networks. In such selection method, domain IDs of the home networks are stored in the mobile communication device in advance. Among the access points satisfying predetermined quality, the mobile communication device preferentially selects an access point having a home network domain ID. If none of the access points have a home network domain ID, the mobile communication device is allowed to connect to an access point having a different domain ID.
In addition, as a method for determining whether to allow a mobile communication device to connect to an access point, a handover method has been proposed. In this method, a mobile communication device automatically starts connecting to a wireless system, depending on its wireless link quality. In the handover method, a user presets a connection priority level that is associated with a system identifier of the wireless system. In addition, a connection threshold having a negative correlation with the connection priority level is calculated and associated with the system identifier. When the mobile communication device detects a wireless system, if the wireless link quality of the wireless system is above a connection threshold that corresponds to the system identifier of the wireless system, the mobile communication device automatically connects to the wireless system. The smaller the connection threshold associated with the wireless system is, the more easily the mobile communication device is connected to the wireless system. In addition, the larger the connection threshold associated with the wireless system is, the less easily the mobile communication device is connected to the wireless system.
See, for example, the following documents:
Japanese Laid-open Patent Publication No. 11-205342
Japanese Laid-open Patent Publication No. 2004-304399
As described above, there is a mobile communication device that automatically connects to an access point if the mobile communication device determines that the access point satisfies a predetermined condition and that the signal level received from the access point is above a connection threshold. In addition, in recent years, many facilities such as shops have provided access points in their establishments. Therefore, many access points are found throughout a town. As a result, while a user is travelling in town, the user's mobile communication device could repeatedly be connected to and disconnected from various access points. Such repetition is considered to be a problem. By repeatedly being connected to and disconnected from access points, power consumption of the mobile communication device could be increased. In addition, wireless communication using another wireless system such as a mobile phone network could be affected (for example, wireless communication may be disconnected).
It is also desirable that connection to an access point located at a user's home or office be promptly established and not easily disconnected so that stable wireless communication is achieved. To address the above issues, there is a method in which a user sets a connection priority level to each access point and applies a different connection threshold per access point. According to this method, an access point located at a user's home or office is easily connected by setting a higher priority level (setting a lower connection threshold), and access points located in town are less easily connected by setting lower priority levels (setting higher connection thresholds).
However, if the user needs to set a connection priority level for each access point, much burden is placed on the user in setting operations. This is considered to be a problem.